NATURAL GAS FUEL NATURAL GAS FUEL PROCESSING EXPERIENCE AND PROCESSING EXPERIENCE AND
ISSUESISSUES
SECA Core Technology Program (CTP) workshop
S. Katikaneni, P. S. Patel, H. C. Maru
FuelCell Energy Inc.3 Great Pasture Rd, Danbury, CT 06813
February 14, 2001
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OVERVIEW
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• Natural Gas Composition• Issues and Current Approach• Internal Reforming• Recommendation for Core Technology Program
US PIPELINE NATURAL GAS COMPOSITION REPRESENTING 90% OF THE US SUPPLY
PROPERTY RANGE/LIMITSCompositionMethane, vol%Ethane, vol%Propane,* vol%Pentane, vol%Unsaturated Hydrocarbons
Inert Gases- Nitrogen, vol%- Carbon Dioxide, vol%
Oxygen, vol%
80 – 1000 – 100 – 3
0 – 1.25None
0 – 50 – 30 – 3
0 – 0.2*
ImpuritiesTotal Sulfur, ppmv-
H2S-COS-
Odorants (thiophenes, mercaptans, etc.)
- Halogens (Cl, etc.)
0 – 120 – 120 – 1.00 – 2.0None
Heating Value, Range- LHV, Btu/scf- HHV, Btu/scf
870 – 1000970 – 1100
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* Peak showing may be higher (0.5-10%)
ODORANT COMPOSITION IN US PIPELINE NATURAL GAS
Natural GasOdorant Blend
All MercaptanBlend
Mercaptan/AlkylSulfide Blend
Thiophene/Mercaptan Blend
Thiophene(99.9%)
Natural GasOdorant MarketShare, %
40 - 55 40 - 55 5 <1
CompositionBreakdown
Sulfide Content isUsually 20-50%but can be 70-90%in Limited Areas
Thiophene Contentis Usually 30-50%but can be ~70% inLimited Areas
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REQUIREMENTS FOR NATURAL GAS OPERATION
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Component in Natural Gas Consideration Approach
CH4 Carbon FormationDuring heat-up
Steam additionNon-Catalytic SurfacesCarbon Resistance
Pre-Catalyst ReformingCarbon FormationHHC
Diluents: N2; CO2
Contaminants- H2S
- Organic Sulfur
- Oxygen
Parasitic Losses -
Catalyst PoisoningHardware Corrosion
Organic Sulfur
Uncontrolled Heat Release,Corrosion
Clean-up to subppm level(Sulfur Tolerant Anode)
May require HDS
Pre-oxidizer (pt-Catalyst)
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ROOM TEMPERATURE HIGH CAPACITY SORBENTS ARE DESIRABLE
ActivatedCarbon/Zeolite
Iron
ZincOxide
ActivatedCarbon/Zeolite
ZincOxide
ActivatedCarbon/Zeolite
ZincOxide
10
30
70
150
800
750
SystemComplexity
RelativeCapacity
Temperature,OF
Iron
Iron
TEST SET-UP FOR NATURAL GAS CLEAN-UPRoom Temperature System
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RELATIVE AMOUNTS AND COSTS OF SORBENTS USED TO TREAT 1.0 MMSCFOF PIPELINE NATURAL GAS AT FCE DANBURY POWER PLANT
7
4.4
0.5
3
8.6
0.4
0
1
2
3
4
5
6
7
8
9
10
VOL. (CU. FT.) COST ($1000)
A B C
A
B C
Small Volume Purchase
CA
TALY
ST V
OLU
ME/
CO
ST, F
T3/$
1000
REACTIONS FOR NATURAL GAS -SOFC
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OPTION
Steam Reforming CH4 + 2H2O CO2 + 4H2
REACTIONS
Direct Oxidation
Partial Oxidation CH4 + O2 CO2 + 2H2
CH4
CO2 + H2O + e¯
+Q
+O=-Q
OPTIONS FOR NATURAL GAS PROCESSINGFOR USE IN SOFC
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PROCESS
Steam Reforming High Efficiency
Simple System
BENEFIT
Rapid Response
Direct Oxidation
Partial Oxidation
Steam Management
Carbon Formation
Reduction in EfficiencyNOx Formation
TRADE-OFFCONSIDERATION
INTERNAL REFORMING IN SOFC
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CH4 + H2O CO2 + 4H2 - Q
O=
H2 + O= H2O + 2e- + Q
½ O2 + 2e- O=AIR
CH4
WHY INTERNAL REFORMING
• MAXIMIZES THERMODYNAMIC EFFICIENCY
• EFFICIENT COOLING OF FUEL CELL (DIRECT CONTACT)
• BENEFITS OF SYNERGISTIC REACTONS
• LOWER TEMPERATURE REFORMING HARDWARE
• REDUCED STEAM REQUIREMENTS
• REDUCED COOLING AIR FLOW (<2 STOICH FEASIBLE)
• POTENTIALLY COMPACT AND LOWER COST SYSTEM
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EFFECT OF REFORMER TEMPERATURE ON METHANE STEAM REFORMING
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CARBON FORMATION LINES FOR METHANE/METHANOL/ETHANOL STEAM REFORMING
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REFORMING ACTIVITY MEASURED FOR DIFFERENT FUELS
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FUELOXIDANT
OXIDANT
NATURALGAS
REFORMER
UNIT
DIR CELL
PACKAGE
IIRCATALYST
DIRCATALYST
PARTIALLYREFORMED
FUEL
DFC® STACK CONCEPT
10kW INDIRECT INTERNAL REFORMING PLATE
PLACED IN BETWEEN A GROUP OF CELLS IN A STACK
MF0965
OVERALL DESIGN PARAMETERS ANDTECHNICAL CONSIDERATIONS
PARAMETER(Operational)
TECHNICAL CONSIDERATIONMethod of Heat Supply, Maximum Allowable Heat Flux
Water Supply
Thermal Management, Fuel Supply at Peak Power
Control System Response Rates, Lag in Response Due to Reformer,Boiler and HEXThermal Management (Hot Spots)
Water Recovery
Burner Efficiency
Catalyst Life
Simplicity
Shock Resistance, Hot Spots
Simplicity, Accessibility
Start-up Time
Cold-start Temperature
Peak to Rated Power Ratio
Response time (Rated to Peak)
Time at Peak
Water Self-Sufficiency
Emissions
System Life
Reliability
Safety
Serviceability
(Continue)
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OVERALL DESIGN PARAMETERS ANDTECHNICAL CONSIDERATIONS (Cont’d)
PARAMETER TECHNICAL CONSIDERATION
Packaging (ft3/kW, lbs/kW peak)
Overall Efficiency (Rated, Avg.)
Cost ($/kW, Rated)
Repairs and Maintenance Costs
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Component Sizes, Interconnection, Weight, Simplicity
Thermal Losses, Parasitic Power, Idle Fuel Consumptions
Component Costs, Assembly and Installation costs
Simplicity, Reliability, Serviceability, Variable Costs
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RECOMMENDATIONS FOR CORE TECHNOLOGY PROGRAM
AREA OPPORTUNITY/BENEFIT
Sulfur Tolerant Anode Reduce op. and capital costs system simplification
Low Temperature Sulfur Sorbent System simplification
Reforming Catalyst with Low SootFormation Tendency
Reduced steam requirement, lower cost
Variable Activity Reforming Catalyst Efficient cooling of stack (robust design)
High Rate Heat Exchangers Rapid response (transportation application)
Direct Oxidation Simple, low cost system with rapid response
